View source for Advanced-C++/C2/Constructor-And-Destructor/English-timed

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|'''Time'''
|'''Narration'''

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| 00:01
| Welcome to the '''spoken tutorial''' on '''Constructors and Destructors''' in '''C++'''.

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| 00:07
| In this tutorial, we will learn:

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| 00:09
|* '''Constructors'''

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| 00:10
|* '''Types of constructors'''

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| 00:12
|* '''Destructors.'''

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| 00:13
| We will do this with the help of some examples.

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| 00:17
| To record this tutorial, I am using:

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| 00:20
|* '''Ubuntu Operating System''' version 11.10,

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| 00:23
|* '''g++''' '''Compiler''' version 4.6.1.

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| 00:28
| Let us start with an introduction to '''Constructors. '''

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| 00:31
| A '''constructor''' is a member function.

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| 00:33
| It has the same name as the '''class name'''.

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| 00:37
| '''Constructors''' cannot return values.

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| 00:40
| It is automatically called when an '''object''' is created.

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| 00:44
| Types of '''Constructors''' :

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| 00:46
|* '''Parameterized Constructors.'''

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| 00:49
|* '''Copy Constructors.'''and

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| 00:50
|* '''Default Constructors.'''

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| 00:53
| Let us move on to '''Destructors'''.

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| 00:56
| '''Destructors''' are used to deallocate memory.

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| 00:59
| They are called when an '''object''' is destroyed.

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| 01:02
| A '''destructor''' takes no arguments and has no '''return types'''.

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| 01:07 
| Let us see an example on '''Constructors''' and '''Destructors'''.

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| 01:11
| I have already typed the code on the '''editor''', I will open it.

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| 01:15
| Note that our filename is '''cons hyphen dest dot cpp'''.

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| 01:20
| In this program, we will perform the addition of two numbers using '''constructor.'''

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| 01:25
| Let me explain the code now.

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| 01:27
| This is our '''header file''' as '''iostream'''

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| 01:30
| Here we have used '''std namespace.'''

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| 01:33
| Then we have class '''Addition'''. 'a' and 'b' are the '''integer variables'''.

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| 01:38
|These are the '''private''' members of class '''Addition.'''

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| 01:42
| Here we have the''' Public''' '''specifier.'''

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| 01:44
| Then we have the '''construtor''' '''Addition'''.

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| 01:47
| The '''constructor''' has the same name as the '''class''' name.

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| 01:52
| We have passed two '''arguement'''s here.

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| 01:54
| Now we have defined a '''Destructor.'''

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| 01:57
| For this we use a '''tilde''' sign followed by the '''destructor's''' name.

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| 02:02
| This is a '''public''' function '''add.'''

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| 02:05
| It returns sum of 'a' and 'b'. 

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| 02:08
| Here, we access the '''constructor''' using the '''scope resolution operator.'''

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| 02:12
| 'a' and 'b' are '''private''' members.

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| 02:15
| To access the private members, we use 'x' and 'y'.

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| 02:19
| Then we access the '''destructor.'''

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| 02:21
| In this, we print '''Memory Deallocation.'''

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| 02:25
| This is our '''main function.'''

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| 02:28
| Here, we create an object '''obj''' of '''class''' '''Addition'''. 

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| 02:32
| Then we pass two '''argument'''s as '''3''' and '''4'''.

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| 02:36
| '''3''' will be stored in 'x' and '''4''' will be stored in 'y'.

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| 02:40
| This means 'a's value is '''3 '''and 'b's value is '''4.'''

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| 02:45
| The '''constructor''' that has '''argument'''s is called '''parameterized constructor.'''

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| 02:50
| Hence this one is the '''prameterized constructor.'''

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| 02:53
| Here, we call the function '''add '''using the object''' obj'''.

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| 02:58
|And we '''print''' the sum. 

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| 03:00
| This is our '''return''' statement.

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| 03:02
| Now let us '''execute''' the program.

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| 03:05
| Open the terminal window by pressing '''Ctrl, Alt and T''' keys simultaneously on your keyboard.

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| 03:12
| To compile, type: '''g++ space cons hyphen dest dot cpp space hyphen o space cons'''

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| 03:21
| '''Press Enter'''. 

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| 03:23
| Type: '''dot slash cons'''

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| 03:25
| Press '''Enter'''.

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| 03:27
| The output is displayed as: 

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| 03:29
| '''Sum is 7''' and '''Memory Deallocation'''.

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| 03:33
| Now let us see an example on '''Default constructors.'''

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| 03:37
| Come back to our program.

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| 03:39
| I have already typed the code.

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| 03:41
| Note that our filename is '''default dot cpp'''

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| 03:45
| If a '''constructor''' is not declared in the '''class, '''

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| 03:48
| then the '''compiler''' assumes a '''default constructor''' for the '''class'''.

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| 03:53
| Let me explain the code.

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| 03:55
| This is our '''header file''' as '''iostream.'''

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|  03:58
| Here we have used '''std namespace.'''

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| 04:02
| Then we have '''class Subtraction.'''

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| 04:04
| Then we have 'a' and 'b' declared as''' public.'''

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| 04:08
| Here, we have '''sub''' function.

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| 04:10
| We have passed two '''arguments int a '''and''' int b.'''

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| 04:15
| This returns the subtraction of two numbers 'a' and 'b.'

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| 04:19
| This is the '''defalut constructor.'''

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| 04:22
| Here, we access the default constructor using the''' scope resolution operator.'''

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| 04:27
| This is our '''main''' function.

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| 04:29
| In this we have defined a variable 'x.'

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| 04:34
| Here we create an '''object''' 's' of class '''subtraction.'''

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| 04:39
| Then we call the function '''sub '''using the''' object s.'''

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| 04:42
| And pass two''' arguments '''as''' 8 '''and''' 4.'''

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| 04:47
| Then the result is stored in variable' x.'

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| 04:51
| And here we '''print''' the difference.

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| 04:54
| This is our '''return''' statement.

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| 04:56
| Now, let us '''execute''' the program.

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| 04:58
| Come back to our '''terminal'''.

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| 05:01
| Let us compile, type: '''g++ space default dot cpp space hyphen o space def'''

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| 05:09
| '''Press Enter'''.

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| 05:10
| Type: '''dot slash def'''

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| 05:12
| '''Press Enter'''.

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| 05:14
| The output is returned as:

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| 05:16
| '''Difference is 4'''.

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| 05:18
| Come back to our program.

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| 05:20
| Here you can see that we have passed the '''argument'''s within the '''function'''.

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| 05:25
| And in our previous example, we have passed the arguments within the '''Object.'''

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| 05:30
| And here we have passed the arguments using the '''Object.'''

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| 05:34
| Now let us go back to our '''slide'''s.

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| 05:38
| Let us summarize. In this tutorial we learned:

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| 05:41
|* '''Constructors.''' eg. '''Addition'''

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| 05:43
|* '''Parameterized Constructor.''' eg. '''Addition obj (3, 4);'''

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| 05:48
|* '''Destructors.''' eg.''' ~Addition'''

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| 05:52
|* '''Default Constructor.''' eg. '''Subtraction'''

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| 05:55
| As an assignment, create a '''class''' named '''Division.'''

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| 05:59
| Create a '''constructor''' for the '''class'''.

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| 06:01
| And Create a function '''divide''' which divides two given numbers.

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| 06:06
| Watch the video available at the link shown below.

|-
| 06:09
| It summarizes the Spoken Tutorial project.

|-
| 06:11
| If you do not have good bandwidth, you can download and watch it.

|-
| 06:16
| The Spoken Tutorial Project Team, Conducts workshops using spoken tutorials. .

|-
| 06:21
| Gives certificates to those who pass an online test .

|-
| 06:25
| For more details, please write to:

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| 06:27
| contact@spoken hyphen tutorial dot org

|-
| 06:31
| Spoken Tutorial Project is a part of the "Talk to a Teacher" project.

|-
| 06:36
| It is supported by the National Mission on Education through ICT, MHRD, Government of India.

|-
| 06:42
| More information on this mission is available at the link shown below.

|-
|  06:47
| This is Ashwini Patil from IIT Bombay, signing off. Thank You for joining. 

|}